The least likely culprit of a disfunctioning derailleur is the derailleur itself.

Detach the cable and re-setup the front derailleur: http://www.parktool.com/repair/readhowto.asp?id=75

While the cable is detached, feel how smoothly or roughly it moves in the housing (if the bike has down tube shifters, there may not be any housing for the front) and under the bottom bracket.

It may be the FD after all, try putting some light oil on the springs.